When something's effect is gradually disappearing, the phrase "wearing off" is often used. However, there are several other terms that can be used to convey the same meaning. One alternative is "fading away," which highlights the gradual nature of the dissolution of the effect. Another expression is "diminishing," which conveys a similar sense of the effect becoming less noticeable. "Losing its grip" is another synonym that emphasizes the lessening of the impact. Finally, "weakening" is another term that emphasizes the effect's diminishing strength. These synonyms offer writers and speakers a variety of options to express the idea of something's effect waning over time.